Background shorthand with repeat only sets its background-repeat subproperty. In such case, the other background subproperties are set to their initial values: 'background-image' is set to 'none', 'background-color' is set to transparent, 'background-attachment' is set to 'scroll', 'background-position' is set to '0% 0%'.

Check if 'background-repeat' is 'round', then the width and height of the corresponding background image is rescaled so that they fit a whole number of times (2 in this test) in the background positioning area. Therefore the used width and height of the background image in this test should be 110px.

The 'background-repeat: space' declaration must space out images in one or more dimensions so they fit a whole number of times in the background positioning area. The first and last images in each row and column must sit along edge(s) of the background positioning area.

'Background-repeat: space' when background positioning area is 'padding-box'

When 'background-repeat: space' and background positioning area is set to 'padding-box' the image is repeated as often within the 'padding-box' without being clipped, the images are spaced out to fill the area and the first and last images touch the edges of the 'padding-box'.

Check if 'background-size' is 'auto 61px' and 'background-repeat' is 'round', then the height of the corresponding background image is rounded (70px in this test) so that it fits a whole number of times (3 in this test) in the background positioning area, and the width of the background image is rescaled (70px in this test) to keep the original aspect ratio.

Check if 'background-size' is '52px auto' and 'background-repeat' is 'repeat round', then the width of the corresponding background image is 52px and then repeated while the height is first rescaled from 100px to 52px to keep the original image aspect ratio and then to 60px due to 'round'.

Check if 'background-size' is '52px auto' and 'background-repeat' is 'round repeat', then the width is first rescaled to from 100px to 52px and then rescaled to 60px due to 'round' and the height of the corresponding background image is rescaled from 100px to 60px (to keep the original image aspect ratio) and then repeated vertically.

Check if 'background-size' is '20% 30%' and 'background-repeat' is 'no-repeat round', then the height of the corresponding background image is 50px so that it fits a whole number of times (3 in this test) in the background positioning area, and the width of the background image is rescaled to 20% (50px in this test) of the background area.

'Background-repeat: space' when background positioning area is 'border-box'

When 'background-repeat: space' and background positioning area is set to 'border-box' the image is repeated as often within the 'border-box' without being clipped, the images are spaced out to fill the area and the first and last images touch the edges of the 'border-box'.

'Background-repeat: space' when background positioning area is 'content-box'

When 'background-repeat: space' and background positioning area is set to 'content-box' the image is repeated as often within the 'content-box' without being clipped, the images are spaced out to fill the area and the first and last images touch the edges of the 'content-box'.

Background shorthand with attachment only sets its background-attachment subproperty. In such case, the other background subproperties are set to their initial values: 'background-image' is set to 'none', 'background-color' is set to transparent, 'background-repeat' is set to 'repeat', 'background-position' is set to '0% 0%.

Background shorthand with position only sets its background-position subproperty. In such case, the other background subproperties are set to their initial values: 'background-image' is set to 'none', 'background-color' is set to transparent, 'background-repeat' is set to 'repeat', 'background-attchment' is set to 'scroll'.

When 'background-clip' is set to 'padding-box', then the background painting area is clipped at the edges of the padding of the element. In this test, the padding box is 0px tall and as wide as the body element; therefore, red should not be visible.

When 'background-clip' is set to 'border-box', then the background painting area is clipped at the edges of the borders of the element. In this test, the border box is 96px tall and 96px wide and is made from only the borders.

When 'background-clip' is set to 'content-box', then the background painting area is clipped at the edges of the content of the element. In this test, height is 'auto', therefore its used value is '0px'; width is 'auto', therefore its used value is as wide as the body element. So, the content box is 0px tall and as wide as the body element; therefore, red should not be visible.

Check if 'background-size' is '50% auto', then it rescales the background image so that exactly two copies fit the background positioning area (it is 150px by 150px in this test) horizontally. Therefore the used width of the background-size in this test should be 75px.

Check if 'background-size' is '100% 100%' that it rescales the background image independently in both dimensions to completely cover the background positioning area (it is 150px by 150px in this test), and then the background image is clipped to fit into the content area (it is 100px by 100px as background-clip is 'content-box').

Check if 'background-clip' is 'padding-box', 'background-origin' is 'border-box', 'background-position' is 'top left' (the initial value), and the element has a non-zero border, that expecting the top and left of the background image will be clipped.

Check if 'background-size' is '100% 100%' that it rescales the background image independently in both dimensions to completely cover the background positioning area (it is 100px by 100px as background-origin is 'content-box'). In this test, the background-image should be scaled from 40px wide and 20px tall to become 100px by 100px.

Check if 'background-size' is '50% auto', then it rescales the background image so that exactly two copies fit the background positioning area (it is 160px by 160px in this test) horizontally. Therefore the used width of the background-size in this test should be 80px.

Check if 'background-size' with initial value implies to the intrinsic width and height of the image are to be used. Therefore the used width and height of the background-size in this test should be 60px and 60px.

Check if 'background-size' has only one value 'auto', then such value is the width of the correspoding image and the second value (corresponding to the height of the background image) is assumed to be 'auto'. An 'auto' value for one dimension is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. Therefore the used width and height of the background-size in this test should be 60px and 60px.

Check if 'background-size' has only one length value, then such value is the width of the corresponding image and the second value (corresponding to the height of the background image) is assumed to be 'auto'. An 'auto' value for one dimension is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. Therefore the used height of the background-size in this test should be 45px.

Check if 'background-size' is '100px', maximum width of the positioning area in length, then such value is the width of the corresponding image and the second value (corresponding to the height of the background image) is assumed to be 'auto'. An 'auto' value for one dimension is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. Therefore the used height of the background-size in this test should be 100px.

Check if 'background-size' has only one percentage value, then such value is the width of the corresponding image and the second value (corresponding to the height of the background image) is assumed to be 'auto'. A percentage is relative to the dimensions of the background positioning area. An 'auto' value for one dimension is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. Therefore the used height of the background-size in this test should be 45px.

Check if 'background-size' is '0%', minimum width of the positioning area in percentage, then such value is the width of the corresponding image and therefore the background image is not to be displayed.

Check if 'background-size' is '100%', maximum width of the positioning area in percentage, then such value is the width of the corresponding image and the second value (corresponding to the height of the background image) is assumed to be 'auto'. An 'auto' value for one dimension is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. Therefore the used height of the background-size in this test should be 100px.

Check if 'background-size' has two values 'auto', then the intrinsic width and/or height of the image should be used. Therefore the used width and height of the background-size in this test should be 60px and 60px.

Check if 'background-size' has one 'auto' and one length values, then the second value is the height of the corresponding background image and the first value (corresponding to the width of the background image) is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. Therefore the used width of the background-size in this test should be 100px.

Check if 'background-size' has one 'auto' and one percentage values, then the second value is the height of the corresponding background image and the first value (corresponding to the width of the background image) is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. A percentage is relative to the dimensions of the background positioning area. Therefore the used width of the background-size in this test should be 45px.

Check if 'background-size' has one length and one auto values, then the first value is the width of the corresponding background image and the second value (corresponding to the height of the background image) is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. Therefore the used height of the background-size in this test should be 100px.

Check if 'background-size' has two length values, then such values are the width and height of the corresponding background image. Therefore the used width and height of the background-size in this test should be 100px and 100px.

Check if 'background-size' has one length and one percentage values, then such values are the width and height of the corresponding background image. Therefore the used width and height of the background-size in this test should be 45px and 45px.

Check if 'background-size' has one percentage and one auto values, then the first value is the width of the corresponding background image and the second value (corresponding to the height of the background image) is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension. Therefore the used height of the background-size in this test should be 100px.

Check if 'background-size' has one percentage and one length values, then such values are the width and height of the corresponding background image. Therefore the used width and height of the background-size in this test should be 100px and 100px.

Check if 'background-size' has two percentage values, then such values are the width and height of the corresponding background image. Therefore the used width and height of the background-size in this test should be 45px and 45px.

Check if 'background-size' is '100% 100%' that it rescales the background image independently in both dimensions to completely cover the background positioning area (it is 100px by 100px as background-origin is 'content-box'). In this test, the background-image should be scaled from 40px wide and 20px tall to become 100px by 100px.

Check if 'background-size' is '50% auto', then it rescales the background image so that exactly two copies fit the background positioning area (it is 160px by 160px in this test) horizontally. Therefore the used width of the background-size in this test should be 80px.

Check if 'background-size' is '50% auto', then it rescales the background image so that exactly two copies fit the background positioning area (it is 150px by 150px in this test) horizontally. Therefore the used width of the background-size in this test should be 75px.

Check if 'background-size' is '100% 100%' that it rescales the background image independently in both dimensions to completely cover the background positioning area (it is 150px by 150px in this test), and then the background image is clipped to fit into the content area (it is 100px by 100px as background-clip is 'content-box').

Check if 'background-size' is 'auto 61px' and 'background-repeat' is 'round', then the height of the corresponding background image is rounded (70px in this test) so that it fits a whole number of times (3 in this test) in the background positioning area, and the width of the background image is rescaled (70px in this test) to keep the original aspect ratio.

Check if 'background-size' is 'auto' and 'background-repeat' is 'repeat', that the background image is shown at its intrinsic size (98px wide by 99px tall in this test) and repeats in both horizontal and vertical to cover the background painting area (the same as background positioning area in this test).

Check if 'background-size' is '52px auto' and 'background-repeat' is 'repeat round', then the width of the corresponding background image is 52px and then repeated while the height is first rescaled from 100px to 52px to keep the original image aspect ratio and then to 60px due to 'round'.

Check if 'background-size' is '50px' and 'background-repeat' is 'repeat', then the background image is shown with a width of 50px and its height is resolved by using the image's intrinsic ratio (in this test, the image's intrinsic ratio is 1:1) and (multiplied by) the size of the other dimension, and then it is repeated in both directions.

Check if 'background-size' is '52px auto' and 'background-repeat' is 'round repeat', then the width is first rescaled to from 100px to 52px and then rescaled to 60px due to 'round' and the height of the corresponding background image is rescaled from 100px to 60px (to keep the original image aspect ratio) and then repeated vertically.

Check if 'background-size' is '25% 25%' and 'background-repeat' is 'repeat', then the background image is shown with a width and height of 25% (in this test, 50px by 50px), and then it is repeated in both directions.

Check if 'background-size' is '20% 30%' and 'background-repeat' is 'no-repeat round', then the height of the corresponding background image is 50px so that it fits a whole number of times (3 in this test) in the background positioning area, and the width of the background image is rescaled to 20% (50px in this test) of the background area.

Check if 'background-size' is 'contain' that it scales the background-image, while preserving its intrinsic aspect ratio (it is 1:1 in this test), to the largest size such that both its width and its height can fit inside the background positioning area. In this test, the background-image should be scaled to become 100px by 100px.

Check if 'background-size' is 'contain' that it scales the background-image, while preserving its intrinsic aspect ratio (it is 1:1 in this test), to the largest size such that both its width and its height can fit inside the background positioning area. In this test, the background-image should be scaled to become 100px by 100px.

Check if 'background-size' is 'cover' that it scales the background-image, while preserving its intrinsic aspect ratio (it is 1:1 in this test), to the smallest size such that both its width and its height can completely cover the background positioning area. In this test, the background-image should be scaled to become 100px by 100px.

Check if 'background-size' is 'cover' that it scales the background-image, while preserving its intrinsic aspect ratio (it is 1:1 in this test), to the smallest size such that both its width and its height can completely cover the background positioning area. In this test, the background-image should be scaled to become 100px by 100px.

When 'background-size' is 'cover', then the background-image is scaled, while preserving its intrinsic aspect ratio (it is 1:1 in this test), to the smallest size such that both its width and its height can completely cover the background positioning area. When 'background-size' is 'contain', then the background-image is scaled, while preserving its intrinsic aspect ratio (it is 1:1 in this test), to the largest size such that both its width and its height can fit inside the background positioning area. In this test, the 2 background-images should be scaled to become 100px by 100px.

When 'background-size' is 'cover', then the background-image is scaled, while preserving its intrinsic aspect ratio (it is 1:1 in this test), to the smallest size such that both its width and its height can completely cover the background positioning area. When 'background-size' is 'contain', then the background-image is scaled, while preserving its intrinsic aspect ratio (it is 1:1 in this test), to the largest size such that both its width and its height can fit inside the background positioning area. In this test, the 2 background-images should be scaled to become 100px by 100px.

Check that given a valid declaration, for each layer the shorthand 'backgound' first sets the corresponding layer of each of 'background-image', 'background-position', 'background-size', 'background-repeat', 'background-origin', 'background-clip' and 'background-attachment' to that property's initial value

Check that given a valid declaration, for each layer the shorthand 'backgound' first sets the corresponding layer of each of 'background-image', 'background-position', 'background-size', 'background-repeat', 'background-origin', 'background-clip' and 'background-attachment' to that property's initial value, then assigns any explicit values specified for this layer in the declaration

Check that given a valid declaration, for each layer the shorthand 'backgound' first sets the corresponding layer of each of 'background-image', 'background-position', 'background-size', 'background-repeat', 'background-origin', 'background-clip' and 'background-attachment' to that property's initial value, then assigns any explicit values specified for this layer in the declaration, and finally 'background-color' is set to the specified color, if any, else set to its initial value